In general, inductive loops and layout thereof in the conventional electromagnetic-induction device arranges inductive loops as check network that are distributed with equidistance in the X-direction and Y-direction of two-dimensional Cartesian coordinates to induce the electromagnetic pen and calculate the absolute position thereof. Referring to FIG. 1A, it shows a layout for inductive loops distributed in the X-direction of two-dimensional Cartesian coordinates, wherein one terminal of each of the inductive loops 110A is connected to each switch (X0 to X7) and the other terminal is electrically coupled with a ground wire 105A, whereby the reduced signal of each of the inductive loops 110A can be detected by controlling the switches (X0 to X7). Because of the inverse proportion of the magnetic field intensity to the square of distance the electromagnetic pen that can emit electromagnetic signal is away from the tablet to result in more and more weak induced signal that is received by inductive loops; on the contrary, the induced signal that is received by inductive loops is an increasing number of intensity when the electromagnetic pen approaches the tablet. Therefore, CPU of the tablet scans one by one and in turn each of the inductive loops to analyze intensity of induced signals that are received by each inductive loops, so as to detect the position where the cordless pen is located and calculate the coordinates thereof.
Referring to FIG. 1B, it shows a layout for inductive loops distributed in the Y-direction of two-dimensional Cartesian coordinates, wherein one terminal of each of the inductive loops 110B is connected to each switch (Y0 to Y7) and the other terminal is electrically coupled with a ground wire 105B, whereby the reduced signal of each of the inductive loops 110A can be detected by controlling the switches (Y0 to Y7). The difference between the inductive loops 110A and the inductive loops 110B is that they are distributed in different directions of two-dimensional Cartesian coordinates. Referring to FIG. 1C, it shows a layout comprising the inductive loops 100A (as FIG. 1A shows) distributed in the X-direction of two-dimensional Cartesian coordinates and the inductive loops 100B (as FIG. 1A shows) distributed in the Y-direction of two-dimensional Cartesian coordinates,
However, in the trend that a electronic device has a need to be multi-function or versatile, a tablet or a electromagnetic-induction device no longer only has a single input mode with electromagnetic induction, but further it is integrated with various kinds of input device, and particular with a touch device, for example a projected capacitance touch device or a capacitive matrix touch device. Therefore, the tablet or the electromagnetic-induction device can be integrated with a touch device to have more input modes and functions.
Because the layout for inductive loops in conventional electromagnetic-induction device is an interlaced layout for inductive loops (as FIG. 1A FIG. 1B shows), it has a need that through holes 102A or 102B are formed at the places where each inductive loop is interlaced with other inductive loops. Therefore, the inductive loops can extend to other layers by the through holes 102A or 102B for preventing the inductive loops from contacting with each other and from the interference resulted from the contact between the inductive loops. Take one inductive loop showed in FIG. 1A as an example, the through holes 102A are formed at the place where the inductive loop connected with the switch X2 and the inductive loop connected with the switch X1 are interlaced at for preventing the inductive loop connected with the switch X2 from contacting with the inductive loop connected with the switch X1. Therefore, the inductive loop connected with the switch X2 extends to another layer or plane, which is different from the layer or plane with the inductive loop connected with the switch X1 deposed thereon, by the through holes 102A. Although in plane view of the layout showed in FIG. 1A, the inductive loop connected with the switch X2 and the inductive loop connected with the switch X1 are interlaced with each other, but in fact, they do not contact with each other because the inductive loop connected with the switch X2 extends to another layer or plane by the through holes 102A. The other inductive loops showed in FIG. 1A, FIG. 1B and FIG. 1C are formed by same method.
Because the foregoing layout for inductive loops of conventional electromagnetic-induction device having only function or mode is formed on a hard circuit board or a flexible circuit board, the through holes and inductive loops are easy to formed, even the layout is formed with complicated and more steps. However, if the conventional electromagnetic-induction is integrated with a touch device, the inductive loops need to be fabricated on the substrate of the touch device. It is difficult to fabricate so many and so small through holes on the substrate of the touch device because the substrate of the touch device and the circuit board are made of such different materials. Accordingly, the difficulty in integrating the conventional electromagnetic-induction device with a touch device increases and the possibility of integrating the conventional electromagnetic-induction device with a touch device decreases. Therefore, in view of foregoing drawbacks of the layout for inductive loops of conventional electromagnetic-induction device, there is a need to provide a new layout for inductive loops of an electromagnetic-induction system without through holes. Besides, it is capable of being integrated with a touch device in the same substrate or medium for fabricating an input device with multi-function.